Electric current collector



} Mrch 28, 1944. M. HANNA 2,345,429

ELECTRIC CURRENT COLLECTOR Filed Oct. 26, 1942 Inventor-z Max 1?.Hanna,

b Wan 1761; HisAttoPney.

Patented Mar. 28, 1944 ELECTREC CURRENT COLLECTOR Max B. Hanna, Erie, Pa., assignor to General Electric Company, a corporation'of New York Application October 26, 1942, SerialNo. 463,322.

4 Claims.

My invention relates to electric current collectors, such as are used with dynamo-electric machines which are provided with commutator or slip rings.

An object of my invention is to provide an improved current collector of the type used for providing electrical contact with a commutator or slip ring.

Another object of my invention is to provide an improved, electric contact brush of the type used as a current collector in dynamo-electric machines.

Further objects and advantages of my invention will become apparent and my invention will be better understood from the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In the drawing, Fig. 1 is a side elevational view of a brush embodying features of my invention; Fig. 2 is a sectional view taken along line 2-2"of'Fig. 3 illustrating an embodiment of my improved current collector; Fig. 3 is a sideelevational view partly broken away, of a dynamoelectric machine end shield provided with an embodiment of my improved current collector; and Fig. 4 is a perspective view of the embodiment oi'my improved contact brush shown in Figs. 2 and 3.

Referring to the drawing, I have shown an embodiment of my'improved electric current collector mounted in an end shield ID of a dynamoelectric machine and adapted to supply current to a commutator II schematically illustrated by a dotted line in Fig. 2. The current collector includes a plurality of contact brushes to which current is supplied from a source of electric power supply through a terminal stud l2 mounted in the'end shield l and supported therein by a pair of electrically insulating bushing l3 and M arranged in openings in the end shield it The terminal stud I2 is held in position by a nut 15 which threadedly engages the outer end l6 thereof and by a cotter pin I! which extends through the stud E2 on the inner side of the bushing [4. The source of electric power supply is adapted to be connected to the stud l2 by securing a terminal to the threaded end It thereof, and current is supplied from the stud 2 to a contact brush through a pigtail or flexible electrical conductors I8 formed of four braids of electrically conductive material which are secured to a brush contact element I!) by a terminal plate. or cap 20: arranged oven one end ofthe contactelement l9. l he contact element l9may be made 0f any-suitab1e material, such as silvergraphite, and the pigtail 18 forms a good electrical contact with the terminal; plate 20- by, be

ing welded to the outer-sid -thereoi. The endoi the pig-tail l8 opposite the contact element I9 is provided with a pair of fiexible-clamping fingers 2| which are secured to the braided conductors.

diameter than the diameter ofthe terminal stud Goodelectrical contact is formed between the terminal stud l2-and the pigtail 18. by merelypushing the fingers 2t over the stud element l2;

l2 to clampingly secure the pigtail to the stud. In some installations-the vibration may require a more secure contact between the pigtail l8,

and the stud l2 and this may be obtainedby providing a terminal-plate-23 soldered or otherwise suitably secured to the outer ends of the pigtail I8'and secured to-the terminal stud Why a screw as shown in Fig. 1.

The brush contact element l9is,; adapted to be biased into good electrical contact with the commutator H by a coi1 spring. -element 24 which is loosely arranged about amounting stud 25 supported by insulatin bushings l3 and 14 in openingsinthe end shield 10. An end 26 of the spring 24 isadaptedto press against the contact element 19 andiis bentangularly over a transversely extending pressure plate portion 21 of a U-section pressure-finger member 28. Each of the two side, portions-of the pressure finger 28 is formed with an opening therein arranged over the supporting stud 25 to provide a pivotal mounting for the pressure finger on this stud. Pressure is applied to the pressure plate portion 21 of the finger by the spring 24 and to the brush IQ for biasing the brush toward the commutator through a spherical or rounded surface pressure contact point element 29 which permits the brush to move or rock in all directions to follow the commutator surface very closely. This contact point 29 is located substantially so that the force resulting from the radial reaction ofthe commutator against the brush combined with the irictional drag on the brush due to the rotation of the commutator, referred to the center of the brush, passes substantially through the point of contact 29, as indicated in Fig. 2. This places the contact point 29 slightly to one side of the center of the pressure plate 2'! toward the trailing edge of the brush, as the average coefficient of friction is equal to the tangent of the angle a? which determines the location of the point 2 9 as explained. With this arrangement the brush exerts substantially uniform pressure against the commutator at both the leading and trailing edges and will have an essentially even rate of wear. This is possible mainly because bf the relatively short brush. The pressure of the spring 24 is obtained by engagement of the outer end of the spring 24 with a curved end 3| of a supporting spring 132,. which is loosely mounted about the terminal stud I 2. In order to prevent the passage of current through the springs 32 and 24, an insulating sleeve 33 is arranged over the curved end 3| of the spring 32 to insulate these two springs from each other. The contact element l 9 is held in its desired position with respect to the pressure finger 28 by a pair of locating pins134 arranged one on each side of the braided pigtail element [8 and secured to the contact'element [9 by being aflixed to the upper side of the terminal plate 20. These pins 34 are adapted to extend through openings 35 formed in the pressure plate 21 of the pressure finger member 28.

When it is desired to inspect or replace a contact brush member, the pressure finger 28 may be lifted to the position shown in the dotted lines in Fig. 2, and an inturned end 36 of the spring 32 away from the insulated end 3| may be hooked under a tab 31 formed on the outer edge of the pressure plate 21 to hold the pressure finger away from the commutator. This construction provides a contact brush which may be very readily replaced or removed for inspection merely bylifting the pressure finger'28 as stated above, which releases the pins 34 from the socket holes 35 in the pressure finger, and disconnecting the end of the pigtail l8 which is clamped about the terminal stud I2 merely by exerting a slight pull on the pigtail or by unscrewing the terminal 23 from the stud I2. A brush also may be very easily placed in position by merely snapping the clamped end 2| of the pigtail l 8 over theterminal stud 12 or screwing the terminal23 to the stud and then placing the contact element {9 in position on the commutator with the pins 34 arranged in sockets 35 of the pressure finger 28.

While I' have illustrated and described particular embodiments of my invention, modifications thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular embodiments disclosed, and I'intend in the appended claims to cover all modifications which do not depart from the spiritand'scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric current collector including a contact element, a flexible electrical conductor having one end thereof secured to said contact element, a pair of locating pins secured to said contact element arranged one on each side of said flexible electrical conductor, and resilient contact element biasing means including a spherical contact surface pressure element slightly on the trailing side of the center of said contact element providing for movement of said contact element -about said spherical surface and for biasing said contact element toward a current collecting member.

2. An electric current collector including a pressure finger, a contact element, a terminal 1, plate secured to said contact element at one end thereof, a pair of locating pins arranged on said terminal plate for cooperation with said pressure finger to locate said contact element relative to said pressure finger, means including a spherical contact surface on said pressure finger providing for movement of said contact element about said spherical surface, and resilient means for exerting a biasing pressure on said contact element by said pressure finger through said spherical surface.

3. An electric current collector including a pressure finger, a contact element, a terminal plate secured to said contact element at one end thereof, a flexible electrical conductor having" one end thereof secured to said contact element by means of said terminal plate, a pair of locating pins arranged on said terminal plate one on each side of said flexible electrical conductor'for cooperation with said pressure finger to locate said contact element relative to said. pressure finger, and means including a spherical contact surface on said pressure finger slightly on the trailing side of the center of said terminal plate providing for movement of said contact element about said spherical'surface. I

4. An electric current collector including a pressure finger having a pair of pin openings therein, a contact element, a terminal plate secured to said contact element at one end thereof, a flexible electrical conductor having one end thereof secured to said contact element by means of said terminal plate, a pair of locating pins arranged on said terminal plate one on each side of said flexible electrical conductor and extending through said openings in said pressure finger to locate said contact element relative to said pressure finger, means including a spherical contact surface on said pressure finger providing for movement of said contact element about said spherical surface, and resilient means for exerting a biasing pressure on said contact element by said pressure finger through said spherical surface.

o MAX R. HANNA; 

